The bench tests for the O4HD were done with our standard set of CD quality, 16 bit, 44.1 kHz test tones played directory from the CD player in the O4HD. I also ran the same tests after importing the test CD into the O4HD which encoded the test tracks in FLAC format.

At 1 kHz, THD+N for CD played directly from the O4HD CD drive was 0.00126%.

At 1 kHz, THD+N for CD (FLAC encoding) played from the O4HD internal hard drive was 0.00125%.

Here are the results for 19 kHz, 20 kHz combined test frequencies for CD played directly from the O4HD CD drive. There is a small visible B-A peak at 1 kHz about 105 dB below 0 dBFS.

Here are the results for 19 kHz, 20 kHz combined test frequencies for CD (FLAC encoding) played from the O4HD internal hard drive. There is a small visible B-A peak at 1 kHz about 104 dB below 0 dBFS.

The IMD measurement for CD played directory from the O4HD CD drive was 0.0006%.

The IMD measurement for CD (FLAC encoding) played from the O4HD internal hard drive was 0.0007%.